Infinitely variable expanding pulley belt gear



W. TGEL April 23, 1940.

INFINITELY VARIABLE EXPANDING PULLEY BELT GEAR Filed May 13, 1938 Patented Apr. 23, 1940 y Parli-:NT OFFICE INFINITELY VARIABLE EXPANDING PULLEY BELT GEAR Walter T-gel, Cologne, Germany, assignor to Koeln Factory of Wilhelm Suelz, Germany Questar, Cologne- Application May 13, i938, serial No. 207,806l

Germany August 1, 1936 2 Claims.

l0, special provisions are made, it is therefore impossible for the belt to have the same tension at all gear ratios. The tension becomes too small below a particular` range of gear ratios, and for other ranges is unduly high, so that damage to, or even 15 breakage of the belt can take place.

'Ihe above disadvantage is avoided if, according to the invention for the purppse of maintaining the desired tension, a roller is provided which bears on the belt with a constant or substantially constant pressure. Preferably the roller bearing on the belt is additional to the expanding pulley or pulleys of the gear, and is mounted on a slidably mounted rod, the setting of which is adjusted in accordance with the gear ratio.

' According to a modification of the invention, instead of employing an additional roller to bear on the belt, only one expanding pulley is employed in conjunction with a V grooved pulley of fixed diameter arranged on the shaft of the gear driving i motor, and this pulley is employed to maintain the desired tension of the belt.

In the preferred constructional formgof such a modified gear, the' motor is arranged aboveg the gear casing on a plate,`which can swingabout an i axis parallel to the axis of themotor and is rotatable under the action of a long spring, preferably within the gear casing, in regard to the double cone pulleys. A

In order that the invention may be more clearly understood and readily carried into practice two Yconstructional examples according to the inven-` tion are shown in the accompanying drawing, in which:

I Figures l and 2 are respectively a side elevation I and a plan view of one form vof gear according l v`with 'right and left handed screw threads. `versely by the same means the spacing between vthe two pulleys may be increased. However when once the desired gear ratio has been established of a common adjustment yoke 6`, whose arm 1 bears on the pulley 3 and arm 8 bears on the pulley 4. The arms 1 and 8 are of course in different planes lying on opposite sides of the belt I. For moving the yoke 6, a Worm 9, a worm wheel I0, and a bolt II attached to the latter are provided, the said bolt II engaging with the yoke 6 and producingsliding thereof in the direction of the axis of the pulleys. The sliding movement of the yoke 6 is guided by guide rodsvI2 and I3, which are fixed in the housing of the gear.

For the purpose of maintaining the desired tension in the belt, according to the invention a roller I4 is' provided. This is rotatablyljournalled at the end of a rod I5, the middle of which is bent as at I6 to pass round one run of the belt and at the other end is slidably mounted in the yoke 6. At the other end the rod I is'provided with a roller I8 which rolls on a cam I9 fixed to the housing, so 4that thev rod I5 is moved outwardly or inwardly accordingto the belt tension and'shape of the. cam I9, as the yoke 6 is moved in the direction of the axes of the pulleys, as explained above. The cam is so shaped that with the various gear ratios ofthe gear obtained by the setting of the yoke 6, the roller I4 always bears on the belt with a constant pressure. The belt can therefore not slacken or become stretched so as to rbecome damaged or broken.

In the modified form of gear illustrated by Figures 3 and 4, only a single double cone expandinggpulley is employed, and the other ,V grooved pulley is ofxed diameter. `Instead of employing an additional roller to bear on the belt with constant pressure, the V-groove pulley of xed diameter,- which is mounted on the shaft of the driving motor, is arranged to be resiliently yielding in regard to the double cone expanding pulley.L

'I'he driving motor is indicated by 20, and 2l indicates the V-groove pulley fastened on the motor shaft. 22 and 23 are the expanding cone pulleys which, in the example shown, are arranged below the motor. Both are adjustable in the axial direction. They are approached together 4if the forks 24 and 25 are brought together by the operation of a hand wheel 21 on a spindle 26 provided Conthe pulleys are only subjected to the action of the belt tension, just as in the case of the first construction herein described.

The cone pulleys' are mounted on shaft 28 passing intothe housing 40, which transmits the energy derived from the motor, by a worm 29A, to the worm wheel 30, and through the shaft 3l of this worm wheel, outside the housing 40 to a belt part of the housing. The end 31 of the spring 36 remote from the arm 32' is adjustable by means of an adjusting device 33 4in known manner so that by this means the tension of the spring canbe varied. Since `the spring arranged in this manner is oi' considerable length, and the arm 35 is relatively short, it follows that a large an` guiar movement of the, plate 33 corresponds to only a small change in the length and tension of the spring. Thus the tension of the belt 39 can be maintained at practically the-same value for all gear ratios. l

What I claim is: v

1. In a motor driven variable speed device, a frame, a motor supporting plate pivoted atvone side to one side ofthe top' of said frame, an arm extending outwardly and downwardly from the pivotal point of said plate and rigidly fixed to the plate, a motor mounted on said plate and provided with adriving pulley, a shaft extending parallel to the axis of the motor and journalled in the lower part ofthe frame, said pulley having a V-grooved face, a pair of confronting frustoconical pulley members splined on'said shaft to form a driven pulley, means to adjust the distance between said pulley members, a V-shaped belt connecting the driving and driven pulleys,

- and :spring means, urging said arm downwardly and inwardly of the frame.

2. In a motor driven variable speed device, a frame, a motor supporting plate pivoted at one vside toone side of the top of said frame, an arm extending outwardly and downwardly from the pivotall point of said plate and rigidly fixed to the plate, a motor mounted on said plate and provided with a driving pulley, a shaft extending parallel to the axis of the motor and journalled in the lower part of the frame, said pulley having -a V-grooved face, a pair of confronting frusto- A conical pulley members splined on said shaft to form a driven pulley, means to adjust the distance between said pulley members, a V-shaped belt, connecting the driving and driven pulleys, a tube extending transversely ofthe frame and opening at one end toward the lower end of the arm, a closure for the other end of said tube and including spring adjusting means, and a spring ha"ing one end connected to the spring adjusting m` .ns

arid its other end. connected to the lower end of said arm.

WALTER TOGEL. 

